1. Field of the Invention
The present invention relates to a breather device in engines, which separates oil mist from blow-by gas containing oil mist and allows the blow-by gas from which the oil mist is removed to be circulated into intake systems.
2. Description of the Related Art
Generally, in four-cycle engines, blow-by gas leaking into a crank chamber from a combustion chamber by passing through a gap between a cylinder and a piston ring is circulated into an intake system so that the gas can be re-combusted. However, when the blow-by gas leaks into the crank chamber, the gas will contain a mist of lubricating oil, or oil mist, in the crank chamber. The oil mist is unfavorably carried to the intake system together with the blow-by gas, resulting in increased consumption of lubricating oil as well as an adverse effect on the engine performance.
In order to solve these problems, there have been proposed various types of breather devices which separate oil mist from the blow-by gas containing the oil mist in the crank chamber so as to supply the blow-by gas having the oil mist removed therefrom to the intake system.
As an example of such a breather device, a breather device disclosed in JP-A-2005-83310 will be described below with reference to FIG. 13 that is a cross-sectional view showing the essential part thereof and FIG. 14 that is an enlarged sectional view of FIG. 13 viewed from an arrow C.
A breather device 100 includes a case-side breather chamber 103, a cylinder-head-side breather chamber, a case-side breather tube 105, a cylinder-head-side breather tube 106, a collecting section 107, and an air-cleaner-side breather tube 108. The case-side breather chamber 103 is provided so as to communicate with a crankcase 101. The cylinder-head-side breather chamber is provided so as to communicate with a cylinder head cover not shown. The case-side breather tube 105 guides the blow-by gas in the case-side breather chamber 103 toward an unillustrated air cleaner. The cylinder-head-side breather tube 106 guides the blow-by gas in the cylinder-head-side breather chamber toward the air cleaner. The collecting section 107 allows the blow-by gas, which is respectively guided by the case-side breather tube 105 and the cylinder-head-side breather tube 106, to be collected. The air-cleaner-side breather tube 108 guides the blow-by gas that is collected to the collecting section 107 toward the air cleaner.
The case-side breather chamber 103 separates the oil contained in the blow-by gas flowing in from the crankcase 101. A case-side joint pipe 109 is mounted above the case-side breather chamber 103. The case-side breather tube 105 is fitted onto the case-side joint pipe 109, whereby the case-side breather chamber 103 and the case-side breather tube 105 are connected to each other through the case-side joint pipe 109.
When the engine is started, the blow-by gas leaking into the crankcase 101 flows into the case-side breather chamber 103, and then passes through the case-side joint pipe 109 and the case-side breather tube 105 to be guided to the collecting section 107. In this case, the oil mist contained in the blow-by gas is separated in the case-side breather chamber 103.
The blow-by gas flowing into the cylinder head cover flows into the cylinder-head-side breather chamber, and then passes through the cylinder-head-side breather tube 106 to be guided to the collecting section 107. In this case, the oil mist contained in the blow-by gas is separated in the cylinder-head-side breather chamber.
The blow-by gas guided by the case-side breather tube 105 and the cylinder-head-side breather tube 106 is collected at the collecting section 107, and sucked into the air cleaner through the air-cleaner-side breather tube 108. In this case, the collecting section 107 functions as a vapor-liquid separating device of the blow-by gas flowing from the cylinder-head-side breather chamber. The separated oil mist is returned to the crankcase 101 through the case-side breather tube 105 and the case-side breather chamber 103 by the action of gravity. The oil mist adhered onto the inside of the air-cleaner-side breather tube 108 is returned to the crankcase 101 through the collection section 107, the case-side breather tube 105, and the case-side breather chamber 103 by the action of gravity.
According to the JP-A-2005-83310, the collecting section 107 serving as the vapor-liquid separating device is provided separately from the main body of the engine, such as the cylinder head, the cylinder head cover, the crankcase, etc., and coupled to these components with the respective tubes. Accordingly, the number of components is increased, whereby the configuration is complicated, which might lead to a troublesome assembling operation and increased manufacturing cost.